Multi-speed transmission having three planetary gear sets

ABSTRACT

A transmission is provided having an input member, an output member, three planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices include clutches and brakes.

FIELD

The invention relates generally to a multiple speed transmission havinga plurality of planetary gear sets and a plurality of torquetransmitting devices and more particularly to a transmission havingseven or more speeds, three planetary gear sets and a plurality oftorque transmitting devices.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission uses a combination of frictionclutches, planetary gear arrangements and fixed interconnections toachieve a plurality of gear ratios. The number and physical arrangementof the planetary gear sets, generally, are dictated by packaging, costand desired speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needfor an improved, cost-effective, compact multiple speed transmission.

SUMMARY

A transmission is provided having an input member, an output member,three planetary gear sets, a plurality of coupling members and aplurality of torque transmitting devices. Each of the planetary gearsets includes first, second and third members. The torque transmittingdevices are for example clutches and brakes.

In another embodiment of the transmission, the transmission has an inputmember, an output member, first, second, and third planetary gear sets.Each of the planetary gear sets has a sun gear, carrier and ring gearmembers. The input member is continuously interconnected to the ringgear member of the third planetary gear set and the output member iscontinuously interconnected to the ring gear member of the secondplanetary gear set.

Moreover, a first interconnecting member continuously interconnects thering gear member of the first planetary gear set with the sun gearmember of the second planetary gear set. A second interconnecting membercontinuously interconnects the carrier member of the first planetarygear set with the carrier member of the second planetary gear set.

Additionally, a first torque transmitting mechanism is selectivelyengageable to interconnect the ring gear member of the first planetarygear set with the carrier member of the third planetary gear set. Asecond torque transmitting mechanism is selectively engageable tointerconnect the input member with the carrier member of the secondplanetary gear set and the carrier member of the first planetary gearset. A third torque transmitting mechanism is selectively engageable tointerconnect sun gear member of the first planetary gear set with thecarrier member of the third planetary gear set. A fourth torquetransmitting mechanism is selectively engageable to interconnect the sungear member of the third planetary gear set with the stationary element.A fifth torque transmitting mechanism is selectively engageable tointerconnect the ring gear member of the first planetary gear set andthe sun gear member of the second planetary gear set with the stationaryelement. A sixth torque transmitting mechanism is selectively engageableto interconnect the carrier member of the first and second planetarygear set with the stationary element. The torque transmitting mechanismsare selectively engageable in combinations of at least three toestablish at least seven forward speed ratios and at least one reversespeed ratio between the input member and the output member.

In yet another embodiment of the present invention a transmission isprovided having a first interconnecting member continuouslyinterconnects the ring gear member of the first planetary gear set withthe carrier member of the second planetary gear set. A secondinterconnecting member continuously interconnects the carrier member ofthe first planetary gear set with the sun member of the second planetarygear set.

Furthermore, a first torque transmitting mechanism is selectivelyengageable to interconnect the carrier member of the first planetarygear set with the carrier member of the third planetary gear set. Asecond torque transmitting mechanism is selectively engageable tointerconnect the input member and the ring gear member of the thirdplanetary gear set with the carrier member of the second planetary gearset and the ring gear member of the first planetary gear set. A thirdtorque transmitting mechanism is selectively engageable to interconnectthe sun gear member of the first planetary gear set with the carriermember of the third planetary gear set. A fourth torque transmittingmechanism is selectively engageable to interconnect the sun gear memberof the third planetary gear set with the stationary element. A fifthtorque transmitting mechanism is selectively engageable to interconnectthe carrier member of the first planetary gear set and the sun gearmember of the second planetary gear set with the stationary element. Asixth torque transmitting mechanism is selectively engageable tointerconnect the ring gear member of the first planetary gear set andthe carrier member of the second planetary gear set with the stationaryelement. The torque transmitting mechanisms are selectively engageablein combinations of at least three to establish at least seven forwardspeed ratios and at least one reverse speed ratio between the inputmember and the output member.

Thus, it is an object of the present invention to provide a transmissionhaving at least seven forward speeds and at least one reverse.

It is further an object of the present invention to provide atransmission having three planetary gear sets, a plurality of couplingmembers and a plurality of torque transmitting devices.

Further objects, aspects and advantages of the present invention willbecome apparent by reference to the following description and appendeddrawings wherein like reference numbers refer to the same component,element or feature.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a lever diagram of an embodiment of an seven speedtransmission according to the present invention;

FIG. 2 is a diagrammatic illustration of an embodiment of an seven speedtransmission according to the present invention;

FIG. 3 is a diagrammatic illustration of another embodiment of an sevenspeed transmission according to the present invention; and

FIG. 4 is a truth table presenting the state of engagement of thevarious torque transmitting elements in each of the available forwardand reverse speeds or gear ratios of the transmission illustrated inFIGS. 2 and 3.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

At the outset, it should be appreciated that the embodiments of theseven speed automatic transmission of the present invention have anarrangement of permanent mechanical connections between the elements ofthe three planetary gear sets. A first component or element of a firstplanetary gear set is permanently coupled to a first component orelement of the second planetary gear set. A second component or elementof a first planetary gear set is permanently coupled to a secondcomponent or element of the second planetary gear set.

Referring now to FIG. 1, an embodiment of a seven speed transmission 10is illustrated in a lever diagram format. A lever diagram is a schematicrepresentation of the components of a mechanical device such as anautomatic transmission. Each individual lever represents a planetarygear set wherein the three basic mechanical components of the planetarygear are each represented by a node. Therefore, a single lever containsthree nodes: one for the sun gear, one for the planet gear carrier, andone for the ring gear. The relative length between the nodes of eachlever can be used to represent the ring-to-sun ratio of each respectivegear set. These lever ratios, in turn, are used to vary the gear ratiosof the transmission in order to achieve an appropriate ratios and ratioprogression. Mechanical couplings or interconnections between the nodesof the various planetary gear sets are illustrated by thin, horizontallines and torque transmitting devices such as clutches and brakes arepresented as interleaved fingers. Further explanation of the format,purpose and use of lever diagrams can be found in SAE Paper 810102, “TheLever Analogy: A New Tool in Transmission Analysis” by Benford andLeising which is hereby fully incorporated by reference.

The transmission 10 includes an input shaft or member 12, a firstplanetary gear set 14 having three nodes: a first node 14A, a secondnode 14B and a third node 14C, a second planetary gear set 16 havingthree nodes: a first node 16A, a second node 16B and a third node 16Cand a third planetary gear set 18 having three nodes: a first node 18A,a second node 18B and an output shaft or member 22.

The input member 12 is coupled to the third node 18C of the thirdplanetary gear set 18. The output member 22 is coupled to the third node16C of the second planetary gear set 16. The first node 14A of the firstplanetary gear set 14 is coupled to the first node 16A of the secondplanetary gear set 16. The second node 14B of the first planetary gearset 14 is coupled to the second node 16B of the second planetary gearset 16.

A first clutch 26 selectively connects the first node 14A of the firstplanetary gear set 14 and the first node 16A of the second planetarygear set 16 with the second node 18B of the third planetary gear set 18.A second clutch 28 selectively connects the third node 18C of the thirdplanetary gear set 18 and input member 12 with the second node 14B ofthe first planetary gear set 14 and the second node 16B of the secondplanetary gear set 16. A third clutch 30 selectively connects the thirdnode 14C of the first planetary gear set 14 to the second node 18B ofthe third planetary gear set 18. A first brake 32 selectively connectsthe first node 18A of the third planetary gear set 18 to a stationarymember or transmission housing 50. A second brake 34 selectivelyconnects the first node 16A of the second planetary gear set 16 and thefirst node 14A of the first planetary gear set 14 to the stationarymember or transmission housing 50. A third brake 36 selectively connectsthe second node 16B of the second planetary gear set 16 and the secondnode 14B of the first planetary gear set 14 to a stationary member ortransmission housing 50.

Referring now to FIG. 2, a stick diagram presents a schematic layout ofthe embodiment of the seven speed transmission 10 according to thepresent invention. In FIG. 2, the numbering from the lever diagram ofFIG. 1 is carried over. The clutches and couplings are correspondinglypresented whereas the nodes of the planetary gear sets now appear ascomponents of planetary gear sets such as sun gears, ring gears, planetgears and planet gear carriers.

For example, the planetary gear set 14 includes a sun gear member 14C, aring gear member 14A and a planet gear carrier member 14B that rotatablysupports a set of planet gears 14D (only one of which is shown). The sungear member 14C is connected for common rotation with a first shaft orinterconnecting member 42. The ring gear member 14A is connected forcommon rotation with a second shaft or interconnecting member 44 andwith a third shaft or interconnecting member 46. The planet carriermember 14B is connected for common rotation with a fourth shaft orinterconnecting member 48. Each of the planet gears 14D are configuredto intermesh with both the sun gear member 14C and the ring gear member14A.

The planetary gear set 16 includes a sun gear member 16A, a ring gearmember 16C and a planet gear carrier member 16B that rotatably supportsa set of planet gears 16D (only one of which is shown). The sun gearmember 16A is connected for common rotation with the third shaft orinterconnecting member 46. The ring gear member 16C is connected forcommon rotation with the output member or shaft 22. The planet carriermember 16B is connected for common rotation with the fourth shaft orinterconnecting member 48 and the fifth shaft or interconnecting member52. Each of the planet gears 16D are configured to intermesh with boththe sun gear member 16A and the ring gear member 16C.

The planetary gear set 18 includes a sun gear member 18A, a ring gearmember 18C and a planet gear carrier member 18B that rotatably supportsa set of planet gears 18D (only one of which is shown). The sun gearmember 18A is connected for common rotation with a sixth shaft orinterconnecting member 54. The ring gear member 18C is connected forcommon rotation with input shaft or member 12. The planet carrier member18B is connected for common rotation with a seventh shaft orinterconnecting member 56. Each of the planet gears 18D are configuredto intermesh with both the sun gear member 18A and the ring gear member18C.

The input shaft or member 12 is continuously connected to an engine (notshown) or to a turbine of a torque converter (not shown). The outputshaft or member 22 is continuously connected with the final drive unitor transfer case (not shown).

The torque-transmitting mechanisms or clutches 26, 28 and 30 and brakes32, 34 and 36 allow for selective interconnection of the shafts orinterconnecting members, members of the planetary gear sets and thehousing. For example, the first clutch 26 is selectively engageable toconnect the second shaft or interconnecting member 44 with the seventhshaft or interconnecting member 56. The second clutch 28 is selectivelyengageable to connect the input shaft or member 12 with the fourth shaftor interconnecting member 48. The third clutch 30 is selectivelyengageable to connect the first shaft or interconnecting member 42 withthe seventh shaft or interconnecting member 56. The first brake 32 isselectively engageable to connect the sixth shaft or interconnectingmember 54 with the stationary element or the transmission housing 50 inorder to restrict the member 54 from rotating relative to thetransmission housing 50. The second brake 34 is selectively engageableto connect the third shaft or interconnecting member 46 with thestationary element or the transmission housing 50 in order to restrictthe member 46 from rotating relative to the transmission housing 50. Thethird brake 36 is selectively engageable to connect the fifth shaft orinterconnecting member 52 with the stationary element or thetransmission housing 50 in order to restrict the member 52 from rotatingrelative to the transmission housing 50.

Referring now to FIG. 3, a stick diagram presents a schematic layout ofanother embodiment of the seven speed transmission 10′ according to thepresent invention. In FIG. 3, the numbering from the lever diagram ofFIG. 1 is carried over with the addition of a prime symbol. The clutchesand couplings are correspondingly presented whereas the nodes of theplanetary gear sets now appear as components of planetary gear sets suchas sun gears, ring gears, planet gears and planet gear carriers.

For example, the planetary gear set 14′ includes a sun gear member 14C′,a ring gear member 14B′ and a planet gear carrier member 14A′ thatrotatably supports a first set of planet gears 14D′ (only one of whichis shown) and a second set of planet gears 14E′ (only one of which isshown). The sun gear member 14C′ is connected for common rotation with afirst shaft or interconnecting member 42′. The ring gear member 14B′ isconnected for common rotation with a second shaft or interconnectingmember 44′. The planet carrier member 14A′ is connected for commonrotation with a third shaft or interconnecting member 46′ and a fourthshaft or interconnecting member 48′. Each of the planet gears 14D′ areconfigured to intermesh with both the sun gear member 14C′ and planetgears 14E′. Each of the planet gears 14E′ are configured to intermeshwith both the ring gear member 14A′ and the planet gears 14D′.

The planetary gear set 16 includes a sun gear member 16A′, a ring gearmember 16C′ and a planet gear carrier member 16B′ that rotatablysupports a set of planet gears 16D′ (only one of which is shown). Thesun gear member 16A′ is connected for common rotation with the fourthshaft or interconnecting member 48′. The ring gear member 16C′ isconnected for common rotation with the output shaft or member 22′. Theplanet carrier member 16B′ is connected for common rotation with thesecond shaft or interconnecting member 44′ and a fifth shaft orinterconnecting member 52′. Each of the planet gears 16D′ are configuredto intermesh with both the sun gear member 16A′ and the ring gear member16C′.

The planetary gear set 18′ includes a sun gear member 18A′, a ring gearmember 18C′ and a planet gear carrier member 18B′ that rotatablysupports a set of planet gears 18D′ (only one of which is shown). Thesun gear member 18A′ is connected for common rotation with a sixth shaftor interconnecting member 54′. The ring gear member 18C′ is connectedfor common rotation with input shaft or member 12′. The planet carriermember 18B′ is connected for common rotation with a seventh shaft orinterconnecting member 56′. Each of the planet gears 18D′ are configuredto intermesh with both the sun gear member 18A′ and the ring gear member18C′.

The input shaft or member 12′ is continuously connected to an engine(not shown) or to a turbine of a torque converter (not shown). Theoutput shaft or member 22′ is continuously connected with the finaldrive unit or transfer case (not shown).

The torque-transmitting mechanisms or clutches 26′, 28′ and 30′ andbrakes 32′, 34′ and 36′ allow for selective interconnection of theshafts or interconnecting members, members of the planetary gear setsand the housing. For example, the first clutch 26′ is selectivelyengageable to connect the third shaft or interconnecting member 46′ withthe seventh shaft or interconnecting member 56′. The second clutch 28′is selectively engageable to connect the input shaft or member 12′ withthe fifth shaft or interconnecting member 52′. The third clutch 30′ isselectively engageable to connect the first shaft or interconnectingmember 42′ with the sixth shaft or interconnecting member 56′. The firstbrake 32′ is selectively engageable to connect the sixth shaft orinterconnecting member 54′ with the stationary element or thetransmission housing 50′ in order to restrict the member 54′ fromrotating relative to the transmission housing 50′. The second brake 34′is selectively engageable to connect the third shaft or interconnectingmember 46′ with the stationary element or the transmission housing 50′in order to restrict the member 46′ from rotating relative to thetransmission housing 50′. The third brake 36′ is selectively engageableto connect the second shaft or interconnecting member 44′ with thestationary element or the transmission housing 50′ in order to restrictthe member 44′ from rotating relative to the transmission housing 50′.

Referring now to FIGS. 2, 3 and FIG. 4, the operation of the embodimentsof the seven speed transmission 10 and 10′ will be described. It will beappreciated that transmissions 10, 10′ are capable of transmittingtorque from the input shaft or member 12, 12′ to the output shaft ormember 22, 22′ in at least seven forward speed or torque ratios and atleast one reverse speed or torque ratio with triple overdrive. Eachforward and reverse speed or torque ratio is attained by engagement ofone or more of the torque-transmitting mechanisms (i.e. first clutch 26,26′, second clutch 28, 28′, third clutch 30, 30′, first brake 32, 32′,second brake 34, 34′ and third brake 36, 36′), as will be explainedbelow. FIG. 4 is a truth table presenting the various combinations oftorque-transmitting mechanisms that are activated or engaged to achievethe various gear states. An “X” in the box means that the particularclutch or brake is engaged to achieve the desired gear state. An “O”represents that the particular torque transmitting device (i.e. a brakeor clutch) is on or active, but not carrying torque. Actual numericalgear ratios of the various gear states are also presented although itshould be appreciated that these numerical values are exemplary only andthat they may be adjusted over significant ranges to accommodate variousapplications and operational criteria of the transmissions 10, 10′. Anexample of the gear ratios that may be obtained using the embodiments ofthe present invention are also shown in FIG. 4. Of course, other gearratios are achievable depending on the gear diameter, gear teeth countand gear configuration selected.

For example with respect to transmission 10, reverse gear is establishedby engaging or activating the first clutch 26, first brake 32 and thirdbrake 36. The first clutch 26 connects the second shaft orinterconnecting member 44 with the seventh shaft or interconnectingmember 56. The first brake 32 connects the sixth shaft orinterconnecting member 54 with the stationary element or thetransmission housing 50 in order to restrict the member 54 from rotatingrelative to the transmission housing 50. The third brake 36 connects thefifth shaft or interconnecting member 52 with the stationary element orthe transmission housing 50 in order to restrict the member 52 fromrotating relative to the transmission housing 50. Likewise, the sevenforward ratios are achieved through different combinations of clutch andbrake engagement, as shown in FIG. 4.

With continuing reference to FIG. 4 and with respect to transmission10′, reverse gear is established by engaging or activating the firstclutch 26′, first brake 32′ and third brake 36′ are engaged oractivated. The first clutch 26′ connects the third shaft orinterconnecting member 46′ with the seventh shaft or interconnectingmember 56′. The first brake 32 connects the sixth shaft orinterconnecting member 54′ with the stationary element or thetransmission housing 50′ in order to restrict the member 54′ fromrotating relative to the transmission housing 50′. The third brake 36′connects the second shaft or interconnecting member 44′ with thestationary element or the transmission housing 50′ in order to restrictthe member 44′ from rotating relative to the transmission housing 50′.Likewise, the seven forward ratios are achieved through differentcombinations of clutch and brake engagement, as shown in FIG. 4.

It will be appreciated that the foregoing explanation of operation andgear states of the seven speed transmissions 10, 10′ assumes, first ofall, that all the clutches not specifically referenced in a given gearstate are inactive or disengaged and, second of all, that during gearshifts, i.e., changes of gear state, between at least adjacent gearstates, a clutch engaged or activated in both gear states will remainengaged or activated.

The description of the invention is merely exemplary in nature andvariations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A transmission comprising: an input member; an output member; first,second, and third planetary gear sets each having first, second andthird members, wherein the input member is continuously interconnectedto the third member of the third planetary gear set and the outputmember is continuously interconnected to the third member of the secondplanetary gear set; a first interconnecting member continuouslyinterconnecting the first member of the first planetary gear set withthe first member of the second planetary gear set; a secondinterconnecting member continuously interconnecting the second member ofthe first planetary gear set with the second member of the secondplanetary gear set; and six torque transmitting mechanisms eachselectively engageable to interconnect at least one of the first,second, and third members with at least another of the first, second,third members and a stationary element, and wherein the torquetransmitting mechanisms are selectively engageable in combinations of atleast three to establish at least seven forward speed ratios and atleast one reverse speed ratio between the input member and the outputmember.
 2. The transmission of claim 1 wherein the third member of thefirst planetary gear set and the first member of the second and thirdplanetary gear sets are sun gears, the second members of the first,second and third planetary gear sets are carrier members, and the firstmember of the first planetary gear set and the third member of thesecond and third planetary gear sets are ring gears.
 3. The transmissionof claim 1 wherein the third member of the first planetary gear set andthe first member of the second and third planetary gear sets are sungears, the second members of the second and third planetary gear setsand the first member of the first planetary gear set are carriermembers, and the second member of the first planetary gear set and thethird member of the second and third planetary gear sets are ring gears.4. The transmission of claim 1 wherein three of the torque transmittingmechanisms are brakes for connecting a plurality of the first, second,and third members to the stationary element and three of the torquetransmitting mechanisms are clutches for connecting a set of the first,second, and third members to another set of the first, second, and thirdmembers.
 5. The transmission of claim 1 wherein a first of the sixtorque transmitting mechanisms is selectively engageable to interconnectthe first member of the first planetary gear set with the second memberof the third planetary gear set.
 6. The transmission of claim 5 whereina second of the six torque transmitting mechanisms is selectivelyengageable to interconnect the input member with the second member ofthe second planetary gear set and the second member of the firstplanetary gear set.
 7. The transmission of claim 6 wherein a third ofthe six torque transmitting mechanisms is selectively engageable tointerconnect the third member of the first planetary gear set with thesecond member of the third planetary gear set.
 8. The transmission ofclaim 7 wherein a fourth of the six torque transmitting mechanisms isselectively engageable to interconnect the first member of the thirdplanetary gear set with the stationary element.
 9. The transmission ofclaim 8 wherein a fifth of the six torque transmitting mechanisms isselectively engageable to interconnect the first member of the firstplanetary gear set and the first member of the second planetary gear setwith the stationary element.
 10. The transmission of claim 9 wherein asixth of the six torque transmitting mechanisms is selectivelyengageable to interconnect the second member of the first planetary gearset with the stationary element.
 11. A transmission comprising: an inputmember; an output member; first, second, and third planetary gear setseach having first, second and third members, wherein the input member iscontinuously interconnected to the third member of the third planetarygear set and the output member is continuously interconnected to thethird member of the second planetary gear set; a first interconnectingmember continuously interconnecting the first member of the firstplanetary gear set with the first member of the second planetary gearset; a second interconnecting member continuously interconnecting thesecond member of the first planetary gear set with the second member ofthe second planetary gear set; and a first clutch mechanism selectivelyengageable to interconnect the first member of the first planetary gearset with the second member of the third planetary gear set; a secondclutch selectively engageable to interconnect the input member with thesecond member of the second planetary gear set and the second member ofthe first planetary gear set; a third clutch mechanism selectivelyengageable to interconnect the third member of the first planetary gearset with the second member of the third planetary gear set; a firstbrake selectively engageable to interconnect the first member of thethird planetary gear set with the stationary element; a second brakeselectively engageable to interconnect the first member of the firstplanetary gear set and the first member of the second planetary gear setwith the stationary element; and a third brake selectively engageable tointerconnect the second member of the third planetary gear set with thestationary element, wherein the clutches and brakes are selectivelyengageable in combinations of at least three to establish at least sevenforward speed ratios and at least one reverse speed ratio between theinput member and the output member.
 12. The transmission of claim 11wherein the third member of the first planetary gear set and the firstmember of the second and third planetary gear sets are sun gears, thesecond members of the first, second and third planetary gear sets arecarrier members, and the first member of the first planetary gear setand the third member of the second and third planetary gear sets arering gears.
 13. The transmission of claim 11 wherein the third member ofthe first planetary gear set and the first member of the second andthird planetary gear sets are sun gears, the second members of thesecond and third planetary gear sets and the first member of the firstplanetary gear set are carrier members, and the second member of thefirst planetary gear set and the third member of the second and thirdplanetary gear sets are ring gears.
 14. A transmission comprising: aninput member; an output member; first, second, and third planetary gearsets each having a sun gear member, a carrier member and a ring gearmember, wherein the input member is continuously interconnected to thering gear member of the third planetary gear set and the output memberis continuously interconnected to the ring gear member of the secondplanetary gear set; a first interconnecting member continuouslyinterconnecting the ring gear member of the first planetary gear setwith the sun gear member of the second planetary gear set; a secondinterconnecting member continuously interconnecting the carrier memberof the first planetary gear set with the carrier member of the secondplanetary gear set; and a first clutch mechanism selectively engageableto interconnect the ring gear member of the first planetary gear setwith the carrier member of the third planetary gear set; a second clutchselectively engageable to interconnect the input member with the carriermember of the second planetary gear set and the carrier member of thefirst planetary gear set; a third clutch mechanism selectivelyengageable to interconnect the sun gear member of the first planetarygear set with the carrier member of the third planetary gear set; afirst brake selectively engageable to interconnect the sun gear memberof the third planetary gear set with the stationary element; a secondbrake selectively engageable to interconnect the ring gear member of thefirst planetary gear set and the sun gear member of the second planetarygear set with the stationary element; and a third brake selectivelyengageable to interconnect the carrier member of the first planetarygear set with the stationary element, wherein the clutches and brakesare selectively engageable in combinations of at least three toestablish at least seven forward speed ratios and at least one reversespeed ratio between the input member and the output member.
 15. Atransmission comprising: an input member; an output member; first,second, and third planetary gear sets each having a sun gear member, acarrier member and a ring gear member, wherein the input member iscontinuously interconnected to the ring gear member of the thirdplanetary gear set and the output member is continuously interconnectedto the ring gear member of the second planetary gear set; a firstinterconnecting member continuously interconnecting the ring gear memberof the first planetary gear set with the carrier member of the secondplanetary gear set; a second interconnecting member continuouslyinterconnecting the carrier member of the first planetary gear set withthe sun gear member of the second planetary gear set; and a first clutchmechanism selectively engageable to interconnect the carrier member ofthe first planetary gear set with the carrier member of the thirdplanetary gear set; a second clutch selectively engageable tointerconnect the input member and the ring gear member of the thirdplanetary gear set with the carrier member of the second planetary gearset and the ring gear member of the first planetary gear set; a thirdclutch mechanism selectively engageable to interconnect the sun gearmember of the first planetary gear set with the carrier member of thethird planetary gear set; a first brake selectively engageable tointerconnect the sun gear member of the third planetary gear set withthe stationary element; a second brake selectively engageable tointerconnect the carrier member of the first planetary gear set and thesun gear member of the second planetary gear set with the stationaryelement; and a third brake selectively engageable to interconnect thering gear member of the first planetary gear set and the carrier memberof the second planetary gear set with the stationary element, whereinthe clutches and brakes are selectively engageable in combinations of atleast three to establish at least seven forward speed ratios and atleast one reverse speed ratio between the input member and the outputmember.